“Mechanical lever to the right of lens” you mean the MU lever, none other exists. Mechanically shutter trips, electronically does not.
And you keep saying what electromagnetic release does. You must be referring to the electromagnet within each lens, which is true for every Bronica of that vintage so all G, E and S lenses. Camera controls speeds after shutter is tripped though. But I read what I do.
Unlike other bodies, release on GS is also electric, I’m not going to argue whether this is a momentary contact or what Bronica calls it “ electromagnetic” as it is probably moot to problem at hand since I have no problems releasing other lenses.
But having two like new 250 lenses with exact same problem I find any shorting suspicious as being the cause. When I get to it I will check on that, never know it might be the case.
The sequence of events when you trip the GS1's shutter button is as follows:
- The shutter button (and electrical switch) trips an electromagnet in the body that releases the mirror mechanism and mechanical lens coupling.
- at the same time, the electronics in the camera engage the electromagnet in the lens to hold the shutter open.
- the mechanical sequence in the body is as follows:
- the mechanical lever connecting the lens (that also cocks the shutter spring in the lens) slides to the shutter closed position
- the mirror lifts, as the does secondary shutter baffle
- the mechanical lever connecting the lens moves to trip the shutter open
-the electronic timer in the body cuts power to the electromagnet in the lens, which then allows the shutter to close.
The Mirror up lever, which is also the mechanical backup shutter release works as follows:
- flipping the lever to the mirror up position:
- mechanically trips the lever connecting the lens to slide to the shutter closed position
- the mirror lifts, as the does secondary shutter baffle
- the mechanical lever connecting the lens moves and trips shutter open
- since there is no power to the electromagnets in the lens, the shutter is tripped at it's 1/500 mechanical speed.
So, if the mechanical releases are working correctly, then the mechanical parts of the lens and body are OK.
Then electrical side is probably the issue.
If the shutter is not staying open for longer shutter speeds, then the issue is the electromagnet in the lens is not getting enough power. This is not your issue.
If the mirror is not going up, then the electromagnet that triggers the body mechanism is not getting enough power. Similarly if you trip the mechanical mirror up, then try the shutter release. This seems to be your issue.
The electromagnets in the Bronicas are NOT momentary pulse circuits (like a lot of later electronic shutters), and need a sustained high current during operation (pulsed system store the pulse energy in a capacitor, so they work with poor batteries - and use less power). As a result, they are sensitive to battery type and condition. For instance, if you set a shutter speed of 1 sec, the electromagnet in the lens must sustain an adequate current for the full 1 second. The manual recommends silver oxide batteries, as they are capable of sustaining a high current. I've had good success with Li-ion batteries too, but Alkalines often do not last long. If the battery is old or depressed, they often do not work. New silver oxide batteries that are past their due dates sometimes do not work.
Since you report that the body works without a lens, it appears that attaching the lens causes the system to draw too much current from the battery. This may be because the battery cannot handle the current draw, or that there is a short in the electrical system that causes excess current draw. Since you have 2 bodies, if the latter is the issue, you should be able to figure out which item is at fault - which body and/or which lens. (Olympus OM4T's were notorious for having resistive shorts, but I have not come across this issue in Bronicas)
I would start with a good battery, and work through the process to identify the root issue.